Rings moving through magnetic fields and magnets through tubes (1 Viewer)

[someth1ng]

Okay, here's a problem...

In the 2005 HSC, if you look at Q9 (MC), the correct answer should be B however the marking scheme states that it is C.

Also, in the 2011 HSC, if you look at Q25, the correct answer should be magnet B comes out first because there is lower change of flux due to the presence of slits and hence, the induced eddy currents are smaller and lower magnitude resulting in less braking - however, if you look at the marking scheme:

•Identifies that magnet B will leave its tube first and supports this by identifying that the falling magnet results in a changing magnetic flux in the tube walls
•Identifies that this will result in eddy currents and breaking effect for magnet A (Lenz’s Law)
•Identifies that because of the slots, there will be smaller eddy currents and no braking for magnet B

It clearly says "no braking" where there clearly is braking.

Should be just assume that when there's a slit on the ring of slots in the tube that no braking with occur?

 

[Kimyia]

Sorry to bring up an old thread but I have just recently come across this. Does someone know what we can do about these types of questions?
In the 2005 question, the answer should be B cause though smaller eddy currents are induced there will still be some braking, not NO breaking.
And in 2011, the same thing. The slotted tube means smaller eddy currents so smaller braking not NO braking.
And yet in both cases, the marking guidelines go against this. So should we write that there is smaller braking or that there is no braking??

 

[someth1ng]

It appears that the Board of Studies seem to want that slots in a tube will cause the magnet to experience NO braking. In reality, this is obviously not true but it's what they want and so, give it to them.